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United States Patent | 5,238,710 |
Ahmad ,   et al. | August 24, 1993 |
A method for the production of ceramic matrix composites by chemical vapor infiltration. The method includes exposing an infiltrated preform to microwave energy, with pressure variation of the reactant gases in the processing chamber and/or temperature variation of the preform during processing, to produce substantially improved composites. The process provides higher deposition rates within the core of the ceramic matrix composite, higher densification which advantageously initiates within the interior of the ceramic matrix composite and proceeds radially outward, and a thick wall ceramic matrix composite with an overall reduced density gradient.
Inventors: | Ahmad; Iftikhar (Fairfax, VA); Paquette; Edward L. (Severna Park, MD); Silberglitt; Richard (Fairfax, VA) |
Assignee: | Technology Assessment & Transfer, Inc. (Annapolis, MD) |
Appl. No.: | 859790 |
Filed: | March 30, 1992 |
Current U.S. Class: | 427/553; 427/226; 427/237; 427/238; 427/253; 427/274; 427/294; 427/383.5; 427/557; 427/585; 427/595 |
Intern'l Class: | B05D 003/02 |
Field of Search: | 427/553,226,237,238,255,274.3,294,253,383.5,557,585,595 |
4580524 | Apr., 1986 | Lackey, Jr. et al. | 118/725. |
4596741 | Jun., 1986 | Endou et al. | 428/368. |
4663230 | May., 1987 | Tennent | 428/367. |
4929328 | May., 1990 | Besmann et al. | 204/279. |
4960640 | Oct., 1990 | Paquette et al. | 428/368. |
Evans et al., A Mathematical Model for Microwave-Assisted Chemical Vapor Infiltration, Mat. Res. Soc. Symp. Proc. vol. 189, pp. 101-107 (1991). I. Ahmad, "Effect of Microwave Heating on the Solid State Reactions and Mass Transport in Ceramics", Abstract of Doctoral Dissertation, University of Florida, 1991. A. S. De, et al. "Microwave (Hybrid) Heading of Alumina at 2.45 GHz: II. Effect of Processing Variables, Heating Rates and Particle Size" Ceramic Transactions, vol. 21, p. 329 (1991). Ahmad, et al., Microwave Power and Electromagnetic Energy, vol. 26, No. 3, p. 128 (1991). A. S. De, et al., "Microwave (Hybrid) Heating of Alumina at 2.45 GHz: I Microstructural Uniformity and Homogeneity" Ceramic Transactions, vol. 21. p. 319, (1991). |